Add support for Python 3.9, drop Python 3.4

Add support for Python 3.9 since it was officially released in October
and drop support for Python 3.4 since it is end-of-life (EOL).

.travis.yml

@@ -7,6 +7,7 @@ python:
   - 3.6
   - 3.7
   - 3.8
+  - 3.9
   - nightly
 env:
   - REMOVE_LOCALES=false

setup.cfg

@@ -29,11 +29,11 @@ classifiers =
   Programming Language :: Python :: 2
   Programming Language :: Python :: 2.7
   Programming Language :: Python :: 3
-  Programming Language :: Python :: 3.4
   Programming Language :: Python :: 3.5
   Programming Language :: Python :: 3.6
   Programming Language :: Python :: 3.7
   Programming Language :: Python :: 3.8
+  Programming Language :: Python :: 3.9
   Topic :: Software Development
   Topic :: Software Development :: Debuggers
   Topic :: Software Development :: Quality Assurance
@@ -48,7 +48,7 @@ project_urls =
 [options]
 packages = find:
 
-python_requires = >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*
+python_requires = >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*
 
 include_package_data = True
 install_requires =